# Momentary Pushbutton latching ON **URL:** \ **Category:** Ignition\ **Created:** [November 2, 2012, 10:23pm UTC](https://forum.inductiveautomation.com/t/momentary-pushbutton-latching-on/5373 "2012-11-02T22:23:15Z")\ **Posts on this page:** 1\ **Showing post:** 61
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [December 16, 2018, 1:56am UTC](https://forum.inductiveautomation.com/t/momentary-pushbutton-latching-on/5373/61 "2018-12-16T01:56:48Z")
A signalling approach to consider to minimize the PLC code required: - Allocate a PLC array tag / file with enough integers to cover all of the momentary button bits you need for your application, plus two more for transmit counter/comparison at the end. Do not create Ignition tags for these PLC tags. - Create a script module in Ignition that holds an array of timestamps for the number of bits needed, plus a persistent counter in a module global. Write two functions: - A message handler that takes a bit number and sets the corresponding timestamp to some number of milliseconds in the future. 150ms or so. - A gateway timer event function that loops through all of the timestamps, treating all in the past as 0 and all in the future as 1, packing the results bitwise into integers, appends the incremented counter, and writes them all to the PLC in a single system.opc.writeValues() call. Does not write to the last register in the array/file. Call every 100ms or so. - Write a few rungs in the PLC to check the last integer against the second to last, run a timer while equal, then copy the Ignition counter to the last register. If/when the timer expires, 200ms or so, (broken comms), fill the array with zeros. - In a client window, create a timer component with a 100ms period. In its actionPerformed method, use system.util.sendMessage() with a specific bit number. - In the same client window, create a momentary button for that bit and bind its value to the timer component’s enabled property. Do not bind it to any tag. Create as many timer/PB pairs as needed, up to the capacity of the PLC array (less the last two words), each with their own bit numbers. Use the corresponding bit in the PLC as a reliable normally-open PB. Any lost messages, lost OPC writes, or Client GUI freezes will yield a zero bit in the PLC. --- _[View the full topic](https://forum.inductiveautomation.com/t/momentary-pushbutton-latching-on/5373)._